Oh, Give the girls a hug. My DD is 9 and we have a GP too.
All the broken bits of your rose, go out and save them. Cut them into 5 or so inch long pieces, cut off all the leaves (remembering which side is up) and stick them 4 inches deep in light potting soil, keep them a little wetter then you would a houseplant and you'll be surprised how many root. It can take over a month, be patient.
The trick to surviving sleepovers (and we have one coming up, 10th Bday) is to Plan and Supervise. Also, don't be afraid to lay down the law on other people's kids. I'm not saying be crazy picky, but my house, my rules. I have never once had any parent say "Well, Suzy ALWAYS gets to take out every toy in the house and leave it wherever and we NEVER make her put her dinner plate in the sink or brush her teeth. And OUR dog likes to be carried around by the ears"
What I do is put all pets on lock-down. Any pets who normally live in kids rooms come out and they and anyone fragile, like the kitten, get locked in my room, which is very off-limits. If the kids are very animal oriented, I will personally supervise a short playtime where I tell all about animal care and ask about their pets. But mostly, I get some craft things, we have crafts, games, dinner, more games, I keep them up really late, we watch a PG movie (and I always check with parents about the movie, you never know, but I make sure it's rated G or PG, the kids always enjoy it even if they want to pretend they're too cool) with lots of popcorn and snacks, then brushing teeth (my house, my rules, I buy cheap toothbrushes just in case) and the kids all get to camp out in the living room with every pillow and blanket in the house.
LOL, Normally they're too wiped out to do anything like get up @ 4:30 and since my DD knows she has to report to me (as in "Mom, we're done making bracelets, can we get out Twister?") the damage stays minimal.
When the sleepover is over , I am wiped out, but doing it this way works for us and we do lots of sleepovers.